The Sea Witch Returns to Once Upon a Time

Ursula will now be joining Cruella de Vil and Maleficent in ABC’s Once Upon a Time.
Entertainment Weekly has announced, Kristin Bauer van Straten will be returning as Maleficent, Victoria Smurfit is confirmed to play Cruella but playing Ursula will be acted by Merrin Dungey.
Ursula first made her grand entrance in season three's Ariel. Then, she was voiced by Yvette Nicole Brown. If anyone remembers the episode, Ursula had a small part as she appeared in Regina's mirror. Now with an actress named, Ursula might take on a corporeal form and hopefully have more to say.
Does the Sea Witch mean Ariel might be returning as well? It would make for a nice surprise if JoAnna Garcia Swisher, also, reprises her role.
But the real question is how will the writers take on all of these characters? Pattern has shown that Once Upon a Time can only handle one villain/ess at a time.
Which vilain or vilainess do you wish Once Upon a Time will bring to life?